Study On Variable Speed Wind Power Generation Used In"Three-in-one" System

At present, the uninterrupted power supply system in China is mainly composed of diesel (gas) oil generators, which not only consume too much non-renewable energy, cause increasingly serious pollution to the environment. With the rapid development of wind power technology, to make full use of renewable resources has become irreplaceable trends. So it’s meaningful for the conservation of energy, protection of the environment and promoting sustainable development to apply the wind turbine technology to the uninterrupted power supply system, which makes cleaner and no-cost wind energy as the first form of energy supply, diesel (gas) oil generator sets auxiliary power supply. Hence a whole set of wind power generation system is needed to apply to this system.For variable speed wind turbine research, this paper focuses on the variable speed constant frequency doubly-fed wind generator, which is the most widely used in the wind power group. The basic principle and structure of the doubly-fed wind generator are described firstly, and the mathematical model is separately established in three-phase stationary coordinate system and the two-phase synchronous rotating coordinate system, its internal electromagnetic and power transfer relations are researched. Second, according to the demand for uninterrupted power supply system, the basic motor rated parameters are determined. Then electromagnet of the motor is designed, which mainly include the determination of some basic parameters of the motor, the design of stator and rotor plate and winding, electromagnetic analysis and calculation. And computer-aided software for electromagnetic design is written to improve the design efficiency. After that, today’s commonly used in finite element analysis software Ansoft is used for finite element analysis on static fields and transient fields with no-load to verify the reasonableness of the design. Then in order to analyze harmonics generated by2000KW doubly-fed wind generator designed in this paper applied to doubly-fed generation system, the model of the doubly-fed wind power generation system for harmonic analysis is built on Matlab/simulink to fast Fourier harmonic analysis (FFT) on the stator side of the current waveform, and some corresponding harmonic suppression devices are adapted to suppress the harmonics. At the end of the paper, the composition of the "three in one" uninterruptible power supply system, working principles and control process are presented in detail, then the control part of the "three in one" system for wind power technology is researched, a certain theoretical basis for the "three in one" in-depth study of the uninterruptible power supply system are provided.